rOKKSTKY IN MINNESOTA.
BY SAMUKIt II. OHKKX.
Tin : Tiun. :
A tree is a woody plant with n single
stem which from natural tendencies di
vides into two or more main branches at
some distance from ( he ground and
takes on what is commonly known as
the tree form.
The most evident parts of a tree are
stem ( commonlycalled trunkbranches ) ,
twigs , roots , buds , leaves , flowers , fruit
and seed.
The stem , branches and roots are
made up of inner bark , outer bark , sapwood -
wood and heartwood. The outer bark ,
sup wood and heartwood are made up of
concentric circles termed annual rings.
During each period of growth two new
rings ore formed one on the outside of
the sapwood and another on the inside
of the outer bark and as we seldom have
more than one season of growth each
year but one ring is formed on the wood
in a year : so that by counting the rings
of wood in the stem we can determine
very closely the age of trees. In very
rare ca es we have two periods of growth
in one year , as in 1S94 , when the drouth
of midsummer ripened up the wood of
the trees by the first of August and the
rains of imtumn started a new growth ,
and caused some trees and shrubs to
flower in October , but such occurrences
are very uncommon and the extra rings
formed are readily detected by their be
ing smaller than ad joining rings and less
distinctly defined. The age of trees
could be told by the rings of the outer
bark nearly as well as by those of the
wood were it not for the fact that the
outer layers of bark fall off as the tree
grows older.
In some experiments the bark of rap
idly growing branches was peeled back
in the spring for a few inches , the wood
covered with tin-foil and the bark re
placed. At the end of the season there
was found a ring of wood outside
of the tin-foil , thus showing where the
annual growth of the tree was made.
The bark covers the whole exterior
surface of the trunk , branches and roots
and serves as a protection. It is made
up of two parts , the outer or corky layer
which is dead bark and the inner or live
bark. These vary much in appearance
and thickness on different kinds of trees.
For instance , on the white birch the
corky layer is pure white , very thin and
tough , while on our white pine it is very
dark brown and often an inch or more
in thickness and quite brittle.
The sapwood is the portion of the
wood next to the bark. It varies much
in thickness in different species and in
trees of the same species ; the most rap
idly grown trees contain the largest
amount. It is the most active portion ot
the wood in the growing tree , and con
tains considerable plant food and more
water than the heartwood.
The heartwood is the wood in the ecu
tor of the trunk and is generally dis-
inguished from the sapwood by its more
compact structure and darker color ,
ihough in some cases it may be lighter
colored than the sapwood. It is also
larder and more valuable for fuel ,
shrinks less in drying , and is more dur
able in contact with the soil than the
sapwood. There is very little movement
of the sap in the heartwood , and it con
tains less water thaii sapwood.
The roots ftirnish water and nourish
ment that the plant receives from the
oil but only the yoiing roots have the
lower of taking up the water and plant
'ood ; the older roots are most useful in
lolding the tree in place. It is common
to classify roots into surface roots and
: ap roots depending on their shape and
the depth they go in the ground. Some
trees have nearly all surface roots , as
he birch and spruce ; others have nearly
all tap roots which often go to a great
depth on dry land as those of the bur
oak , white oak , black walnut and but
ternut. Most of our trees have a com
bination of the two kinds , as the nmple ,
lackberry and ash. Seedling trees of
most kinds have a decided tap root when
young but in many species it ceases to
grow downward when a few years old.
This is true of the red and scarlet oaks
which often have a tap root extending
four feet in depth before the tree has at-
raiiied a oorresponding height above
ground but after about five years large
lateral roots develop and the growth of
the tap root nearly ceases.
Root growth is relatively less to the
extent of ground occupied in moist and
fertile soil than in dry and poor soil but
the roots are proportionately more
branched. In wet seasons the root de
velopment is less for a given plant than
in dry seasons because the roots may
get their needed food and water from a
small area. Nursery trees grown on
moist rich land have a more compact
root system than those grown on poor
land.
At the Minnesota experiment station
a small bur oak growing on dry , gravelly
soil had a tap root that was evidently 20
feet long , while on moist fertile clay
land in the same section such trees prob
ably seldom have tap roots more than
six feet long.
Buds are placed regularly on the
young branches and are said to be eithei
alternate or opposite. When they oc
cur on the stump or on roots they are
not arranged in 0113' regular order.
There ere two kinds of buds ; flowei
buds which develop into flowers am :
fruit , and leaf buds which develop
into leaves and branches. These can
generally bo distinguished from each
other by their shape and si/.e and by cut
ting through them and noting their con
struction. Flower buds are generally
more liable to injury from climatic
changes than leaf buds.
The leaves of our trees very much ii
size and shape. They are simple whei
composed of but one piece as the leaves
of the oak , maple and birch , and com-
lound when composed of more than one
) iece as the leaves of the locxist , ash
and black walnut. Leaves are made up
of a framework filled in with cellular
issue and covered with a thin skin.
This skin has very many small pores in
t called stomata , through which the
ilant takes in carbon dioxide from the
air and gives off ox3'gen and water.
All our trees shed at least a part of
their leaves each year. All the broad
caved trees and the tamarack shed their
entire foliage yearly while our so-called
evergreen trees lose a part of their leaves
each year. The length of time leaves
remain on this latter class of trees varies
from two or three years , in the case of
white pine growing in very severe loca
tions in this section , to perhaps eight
years , in the case of red cedar favorably
ocated. The time that leaves remain
on the branches in the case of evergreens
depends to some extent on the location
and age of the individual tree.
Flowers are parts of the plant especi
ally modified for the reproduction of the
rdant by seed. Both sexual organs may
be located together in the same flower as
those of the basswood , mountain ash
and cherry ; or in separate flowers on
the some plant as those of the birch , oak
and black walnut , or they may be sepa
rate on entirety different plants as in the
willow , poplar , box elder and ash.
The fruit , botanically defined , is the
seed containing area derived from a
single flower. As xised in nursery prac
tice the term is generally applied to seeds
having a fleshy covering or an adjoin
ing fleshy part.
The seed , botanically defined , is the
ripened ovule , but as the term is used in
nursery practice it often includes the
ovary and other parts that may be at
tached to it. What is commonly called
the seed of maple , ash , elm , walnut and
basswood is really the fruit.
The seeds of plants are distributed in
various ways , the most common of
which are (1) ( ) by
DISTUIBUTION
Qf
OF SEEDS.
Wing
the seed up in the air or water and (2) ( )
by animals. The seeds of ash , arbor
vitro , box elder , catalpa , elmmaple , pine
and spruce have wings which allow
them to be blown great distances by the
wind , especiallj' when they break loose
from the upper branches of high trees
during severe winds. The seeds of the
honey locust are not shed from the pod
until after the pod has fallen and as the
pod is ten inches or more long and spiral
ly twisted it may be blown long distances
on level ground or snow crust. The
seeds of the poplars and willows have a
cottony float attachment which buoys
them up in the air. In the cose of the
basswood , the parachute-like bract at
tached to the seed cluster aids in spread
ing the seeds by carrying them through
the air or along the snow crust. The
seeds of mountain ash , wild black cherry ,
